Modem agriculture faces the ever-increasing challenge of meeting the nutritional and industrial demands for high quality food stuffs and plant derived products. For example, approximately one-half of the world's farm land is dedicated to the production of cereal crops. When the direct (e.g., cooked rice and bread) and indirect consumption (e.g., as animal feed for the production of milk, eggs, and meat) of cereal crops are combined, cereals account for about two-thirds of all human caloric intake. Since 1984, the rate of the world's population growth has out paced world cereal production. Thus, there is a need for improved methods of crop production.
Analysts point to the need for increased reliance on artificial crop fertilizers, herbicides, and pesticides in order to meet the world's demand for cereal and other crops. (See, e.g., Proc. Natl. Acad. Sci. USA 96:5929 (1999).) Attempts to increase crop production have mainly focused on one of two proposed approaches. First, there have been attempts to produce more effective fertilizer and nutrient compounds for application (i.e., foliar spraying) to growing crop plants (See, e.g., U.S. Pat. No. 5,797,976). In an alternative approach, various compounds, typically organic acids and natural and synthetic plant hormones, have been used to increase crop production and fruit ripening. It is well known that organic acids are useful in stimulating the growth of plants. It has been theorized that much of the action of organic fertilizers, such as manure, is due to the presence of organic acids. For example, U.S. Pat. No. 5,654,255 describes compositions comprising a mixture of N,N-dimethyl piperidinium salt, hexitol, and optionally, a cytokinesis promoter. Similarly, U.S. Pat. No. 5,604,177, describes a process for increasing plant growth and productivity comprising treating the roots, stems and/or foliage with gamma-aminobutyric acid and succinic acid as metabolizable carbon sources.
Each of these basic approaches requires repeated applications for eliciting the desired effect in crop plants. Thus, the material and application costs of these approaches is high. These approaches inherently result in the application of extraneous and often excessive levels of organic and inorganic nutrients and compounds to farm land, which leads to increased probability of nutrient leaching and eutrophication of adjacent riparian environments. Additionally, application of additional nutrient loads of crop plants does not elevate crop and biomass production where the nutrients are already in sufficient abundance and balance in the soil.
What is needed are cost effective methods and compositions for increasing crop production and controlling plant metabolism and durability (e.g., to environmental stresses) that do not require time consuming and expensive maintenance and repeated applications.